Dear ,
Lets analyze your scenario step by step .
1)When you disconnected your session , the database was not shut down(or not shutdown properly if you tried to do so ) , check alert log file for clarity .
2)Now , the first step resulted in some shared memory segments which are left over
3) Step 2 is the cause of error ORA-01075: you are currently logged on
4)The same steps may recreate the scenario in the particular server .

Now regarding why this is not happening in the other servers , depends on several questions :
1)what OS the other servers are running ?
2)For example , lets consider the scenario where the other server is bounced in the evening(due to any reasons) , and you disconnected your session in the afternoon
you will not get the error .
3)You can analyse the particluar servers alert log file to see what happened .